1.PHYSICAL You get your nose slit like Jake Gittes in Chinatown, drugged like Marlowe in Murder My Sweet, beaten up twice like Marlowe in The Big Sleep or six times like Mike Hammer in Kiss Me Deadly. Them's the perks.
2.EMOTIONAL Is there something phallic about a private dick with a gun? Why do four women flirt with Bogart in the first 15 minutes of The Big Sleep? Some of us go entire lifetimes without that much flirting. But then you have to fall for the heroin who probably isn't a heroine (Brigid in The Maltese Falcon) or if she is, like Evelyn Cross, she's probably deeply mad albeit with good reason. You may end up with the dame as the credits roll but we all know it's not permanent. The girl is normally trouble with a capital T and that rhymes with P and that stands for Prison.
3.MORTAL You can resist anything except temptation and that might come in the form of that strumpet Carmen or because you've deluded yourself that Terry Lennox is your mate so you'll cover for him until the only way to clear up the mess is to go to Mexico and shoot him. Remember, the cops are mostly crooked or stupid, the judges are drunk or bribed and the DA is keener on winning votes than winning convictions, so if there's to be any kind of justice in this world, you'll just have to dispense it yourself.